1. Field of the Invention
The present invention relates to a rotary-body type throttle valve for a spark ignition internal combustion engine, and more particularly to a rotary-body type throttle valve that can reduce flow resistance.
2. Background Art
Various rotary-body type throttle valves for spark ignition internal combustion engines, including one disclosed in Japanese Unexamined Utility Model Publication No. H4-47396, have been utilized in the conventional art.
FIG. 12 is a frontal view (as viewed in an arrow direction from a line XIIxe2x80x94XII of FIG. 13) showing a valve fully-closed state of a conventional rotary-body type throttle valve. FIG. 13 is a cross-sectional view taken along a line XIIIxe2x80x94XIII of FIG. 12. FIG. 14 is a cross-sectional view showing a fully-open state of a conventional throttle valve. FIG. 15 is a cross-sectional view showing a half-open state of a conventional throttle valve.
In these drawings, numeral 01 indicates a valve casing and intake passages 02a, 02b are formed in the inside of the valve casing 01. In the inside of the valve casing 01, a cylindrical recess portion 02d having an axis line 04 intersecting a central axis 02c of the intake passages 02a, 02b is formed. A columnar valve element 03 is fitted into the cylindrical recess portion such that the valve element 03 is rotatable about the axis 04.
The valve element 03 is provided with a communication passage 05 that makes the upstream intake passage 02a and the downstream intake passage 02b communicate with each other. The upstream intake passage 02a and the downstream intake passage 02b sandwich the cylindrical recess portion 02d of the valve casing 01.
Wall portions 06a, 06b of the valve element 03 are disposed outside the communication passage 05. The wall portions 06a,06b are accommodated in the cylindrical recess portion 02d of the valve casing 01 when the throttle valve is in the fully-open state shown in FIG. 14. In FIG. 12, numeral 07 indicates a flow passage at the time of idling.
Since there are no obstacles in the inside of the flow passage, the flow in the fully-open state is ideal in a rotary-body type throttle valve. Therefore flow resistance is maintained relatively low in a fully-open state.
However, when the valve is only partially opened at an intermediate degree, as shown in FIG. 15, the wall portions 06a, 06b of the valve element 03 disposed outside the communication passage 05 protrude into the interior of the flow passage. The cylindrical recess portion 02d that normally accommodates the wall portions 06a, 06b disposed at the outside of the communication passage 05 in the valve fully-open state is now exposed to the flow passage.
As seen in FIG. 15, vortices a, b, c, d are generated and the flow resistance is increased. The increase in flow resistance brought on by the generation of these flow vortices leads to an undesirable pressure loss.
The present invention overcomes the shortcomings associated with the related art and achieves other advantages not realized by the related art.
An aspect of the present invention is to provide a rotary body throttle valve that reduce pressure losses and reduces and/or eliminates flow vortices.
These and other aspects of the present invention are accomplished by a rotary-body type throttle valve for a spark ignition internal combustion engine comprising a valve casing having an interior; an upstream intake passage and a downstream intake passage; an intake passage formed within the interior and having a rotary-body recess portion formed within the intake passage and having an axis line intersecting a central axis of the intake passage; a valve element having a rotary-body shape rotatably fitted into the rotary-body recess portion of the valve casing; a communication passage provided between the upstream and downstream intake passages, the upstream intake passage and the downstream intake passage sandwiching the rotary-body recess portion; and a through hole formed in a first rotary outer surface of the valve element, the through hole directed from the communication passage of the valve element in a direction intersecting the central axis of the communication passage and penetrating the first rotary outer surface of the valve element.
At the time of partial opening of the valve, a portion of the normally resulting vortices is made smaller due to the flow which enters the communication passage through the through hole. Hence, the pressure loss at the time of opening of the valve to an intermediate degree can be decreased.
These and other aspects of the present invention are accomplished by a rotary-body type throttle valve for a spark ignition internal combustion engine comprising a valve casing having an interior; an upstream intake passage and a downstream intake passage; an intake passage formed within the interior and having a rotary-body recess portion formed within the intake passage and having an axis line intersecting a central axis of the intake passage; a valve element having a rotary-body shape rotatably fitted into the rotary-body recess portion of the valve casing; a communication passage provided between the upstream and downstream intake passages, the upstream intake passage and the downstream intake passage sandwiching the rotary-body recess portion; and a groove formed in at least a portion of an inclined wall surface of the upstream intake passage and in parallel with a planar plane including an axis of the upstream intake passage and a rotary axis of the valve element.
At the time of partial opening of the, it becomes possible to make the normally resulting vortices in the flowstream which enter the communication passage even smaller. Therefore, the flow resistance at the time of opening of the valve to an intermediate degree can be further decreased.
These and other aspects of the present invention are accomplished by a A rotary-body type throttle valve for a spark ignition internal combustion engine comprising a valve casing having an interior; an upstream intake passage and a downstream intake passage, wherein the upstream intake passage is formed having a funnel shape, the funnel shape having a cross-sectional area that reduces in cross-sectional area as the upstream intake passage approaches the communication passage; an intake passage formed within the interior and having a rotary-body recess portion formed within the intake passage and having an axis line intersecting a central axis of the intake passage; a valve element having a rotary-body shape rotatably fitted into the rotary-body recess portion of the valve casing; a communication passage provided between the upstream and downstream intake passages, the upstream intake passage and the downstream intake passage sandwiching the rotary-body recess portion; and a through hole formed in a first rotary outer surface of the valve element, the through hole directed from the communication passage of the valve element in a direction intersecting the central axis of the communication passage and penetrating the first rotary outer surface of the valve element.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.